coil voltage

81usgtv6 · #1 (**permalink**) 02-23-2008, 04:19 PM

does any one know what the voltage to the coil is supposed to be in a 81usgtv6 2.5? I'm getting 10v at idle. And a lot of ignition problems. If i ump across the resistor to give the coil the full 12+v most of the problems go away. Can i get a little knowledge here? thanks.

gt601 · #2 (**permalink**) 02-23-2008, 07:53 PM

I may be wrong here but I don't believe that there is supposed to be a resistor on the coil. Someone correct me if I'm wrong. Has some one been monkeying around with your car? Some aftermarket systems like MSD have you install a resistor if you are using a 6A or 6AL box. It should be 12v at the coil. Make sure that all connections are clean at the fuse panel, battery, etc. Bad grounds can also give weird voltage readings in an electrical system.
A description of your ignition issues may help the diagnosis also.

Paul

81usgtv6 · #3 (**permalink**) 02-24-2008, 09:48 AM

the "resistor" i am talking about is two ceramic cylinders bolted side by side. It is mounted on the same mount as the coil and control mod. It has 3 male spade terminals, one on ether end and one in the middle. 12v dc comes from the ignition control mod to one end terminal and the other end terminal(10v dc) goes to the pos. terminal of the coil. The middle terminal(11v dc) goes somewhere else. all known grounds have been cleaned or replaced. This resiting device i have just described is stock for this car( it only has 50k)and have seen it in picts of other alfas. ignition issue of concern is weak orange spark that is remidied if I apply suplimental 12v dc to coil.

karmat · #4 (**permalink**) 02-25-2008, 08:49 PM

The early GTV6s (1981-1982) used ballast resistors with the original coil. The later cars and Milanos don't. If you don't have the original coil (likely you don't) then you don't need 'em. You should have a Bosch EI coil, or similarly rated coil, though, so make sure that's right at least.

Karl

81usgtv6 · #5 (**permalink**) 02-26-2008, 02:06 PM

the bosch coil that i replaced had primary impedance of 1.3 on 200 scale and secondary impedance of 7.1 on 200k scale. car ran ok for 1500 miles. replaced it with a coil that says " use with primary resistance wire or external resistor. it's test results were primary 1.8 on 200 scale and 10.8 on 200k scale. both coils perform better with aux 12v added to + lead of coil. suspect bosh coil not problem. label missing on coil #1 under- term #15 under = teminal #4 at secondary high voltage terminal. do you know the impedance of plug wires? or where to buy new ones? thanks.
glenn

gt601 · #6 (**permalink**) 02-26-2008, 02:46 PM

Quote:

The early GTV6s (1981-1982) used ballast resistors with the original coil.

karmat · #7 (**permalink**) 02-26-2008, 03:32 PM

Quote:

Originally Posted by 81usgtv6

do you know the impedance of plug wires? or where to buy new ones? thanks.
glenn

karmat · #8 (**permalink**) 02-26-2008, 03:33 PM

Quote:

Originally Posted by gt601

You are right! I forgot about that. I got rid of mine on my '81 and installed a the MSD Blaster 2 Coil. The only car I haven't put one of those coils on is my 164S. I've been too lazy. It's sitting in my tool box right now as we speak (err... write). Go out and buy one. They are cheap. ($40.00 US)

chasgtv6 · #9 (**permalink**) 02-26-2008, 06:26 PM

According to my manual, specs are 0.7-1.2 Ohm and 6.9-11.9 kOhm, so it sounds like the coil is OK. My "82 has the same two ceramic resistors on the fender.